Sawdust hopper



June 15, 1943.

E. ZIMMERMAN SAWDUST uoflimn .Filed June 11, 1941 Emil ZimmermanPatented June 1 5, 1943 UNITED STATES PATENT OFFICE SAWDUST HOPPER VEmil Zimmerman, Everett, Wash.

Application June 11, 1941, Serial No. 397,584

Claims.

Sawdust, so-called, is fed to sawdust burners from hoppers havingupwardly flared walls, usually open at their top and having a restrictedthroat at the bottom. This sawdust includes in large measure hoggedparticles of wood, small chips, and the like, and tends to bridge andclog Within the hopper, particularly when it is somewhat wet. The sametendency to bridge and clog within an upwardly flared hopper isencountered in handling other substances. It is impracticable to providemechanically operated means to continually break up the bridging andclogging tendencies, and because of these tendencies the trouble-free,continuous operation of sawdust burners has not heretofore been fullyattained. This tendency, therefore, presents a serious problem to thesatisfactory use of sawdust burners.

Various partition walls have been provided within such sawdust hoppers,which are intended to eliminate these tendencies without mechanicallyinduced movement, but none of them have fully solved the problem. This,I have discovered, appears to be due largely to the relationship betweensuch inserted partitions and the flared walls of the hopper. While suchpartitions may divide the hopper space into smaller chambers, and whilecertain of these chambers may at one time or another have a shape whichpermits free movement of the sawdust downwardly, without clogging orbridging, usually they further restrict the size of the effective throatopening, and a time will arrive in the process of emptying the hopperwhen such partition walls form with adjacent hopper walls, notdownwardly flared, but rather upwardly flared chambers, thereby, as inthe case of the hopper initially, forming a storage space or chamberwherein bridging and clogging of a material part of the capacity of thehopper occurs.

According to the present invention clogging and bridging of the sawdustor other contents of the hopper is prevented, without any mechanicallyinduced movement, and therefore simply and cheaply, by pendant andfreely swinging partition strips which are arranged in a novel manner,so that, purely by the manner in which the hopper is filled and emptiedit tends to present always to the throat a chamber which is larger atits bottom than at its top, or at least not greater in size at its topthan at its bottom, and having a bottom cross section which does notmaterially extend outside the outline of the hopper throat.

It is a further object to provide a device of this nature which willoperate automatically, solely by reason of theformation and weighting ofthe elements, which is simple and inexpensive, which is not likely toget out of order, and which may be arranged for ready removal, in caseit is desired to have access to the interior of the hopper.

With these and other objects in mind, as will appear hereafter ingreater detail, my invention comprises the novel combination of such ahop per with such clog-preventing means, and the novel clog-preventingassembly per se, as shown in the accompanying drawing, described in thisspecification, and as will be more particularly pointed out by theclaims which terminate the same.

In the accompanying drawing I have shown my invention incorporated in ahopper, all in a representative form as now preferred by me.

Figure 1 is a vertical section through the hopper, illustrating theclog-preventing device in position therein, and Figure 2 is a plan viewof the same.

The hopper as shown is largely conventional. It is shown with upwardlyflared walls I, leading upwardly from and defining the throat 2 at thebottom, and open at its top. While dimensions of course are immaterial,it will be helpful in understanding the principles of the invention itrepresentative dimensions are given. Thus, for instance, the throat maybe a square 10 inches long on each side. The hopper at its top may besquare and 26 inches along each side, and it may be 36 inches high. Itcan be seen that the interior of the hopper converges rather sharplydownwardly to the hopper throat, and that the sawdust would tend tobridge and clog as it would tend to move downwardly within this hopper.

Adjacent the upper part of the hopper, as a convenient support is atransverse rod 8. Supported upon this rod or any equivalent means is aframe 8, which when the throat is rectangular would normally berectangular also; that is to say, the frame 3 is similar in shape to theshape of the throat 2. If the throat is round the frame 3 might still berectangular or square or even hexagonal. Preferably the frame 3 isslightly less in extent, as viewed in plan, than the outline or marginof the throat, and the frame is located vertically above the throat.

Pivotally hung 'upon each side of this frame 3 is a partition strip.These partition strips, to distinguish them, have been designated 4, 5,6, and 1, although they are intended to be identical in form andarrangement. Each one is provided with a sleeve 9 at its upper end,fittin about its side of the frame 3, and forming a free pivot supportfor the strip. Each strip is preferably. so

weighted, or its weight is arranged in such fashion, that its lower endtends to swing somewhat outwardly; thus the strips do not hang preciselyvertically, but rather are inclined slightly outwardly. This has beensomewhat exaggerated in the drawing for purposes of clearerillustration.

With relation to the height of the hopper in which this assembly is tobe supported, the strips 4, 5, 6, and l are of such length that when theframe 3 is supported upon the rod 8 the strips hang downwardly from thetop of the hopper almost to the throat 2. They stop somewhat short ofthe throat at their lower ends, but are of sumcient length that if swungmaterially outwardly from their freely hanging positions they willcontact the flared side walls I of the hopper, and will be therebyprevented from swinging farther. To express it differently, the patterndefined by the lower end of the partition strips, when hanging freely,does not materially extend outside the outline of the throat, and isclosely above the throat; even if the partition strips should be swungoutwardly into contact with the side walls of the hopper their patternstill does not materially extend outside the pattern or outline of thethroat.

The strips are preferably of a width, at least at their bottoms, whichis appreciably less than the length of the frame 3 on the correspondingside of the frame.

Thus formed, arranged, and assembled, the partition strips 4, 5, 6, andl cooperate to define between them a central chamber which at its bottomis not materially larger than the outline of the throat 2, and whichupwardly therefrom progressively decreases in cross-sectional extent.This central chamber is directly in line with the throat 2, to dischargethereinto. Surrounding this central chamber are, in the presentinstance, four wedge-shaped chambers defined between each of thepartition strips and the adjacent upwardly flared hopper wall. Theseouter wedge-shaped chambers are, of course, smallest at their bottoms.

In using the invention the clog-preventing assembly, consisting of theframe 3 and the strips 4, 5, 6, and l, is placed within the hopper,suitably supported at the upper end of the hopper. The strips hangfreely, and thereby diverge slightly outwardly at their lower ends. Thehopper is now filled from the top in the normal manner. It is notnecessary to take any care to hold the partition strips in anyparticular position; they will normally remain approximately in theirfreely hung position, for sawdust will fall, not only in the centralchamber, but also in the surrounding chambers, as the hopper is beingfilled. Now, as the sawdust is consumed in the burner which is below thethroat 2, it is replenished by material from above. The material fromabove comes at first only from the central chamber, and since thiscentral chamber has its largest cross section adjacent the throat, andnot materially greater in extent than the outline of the throat, thesawdust falls freely from this central chamber without any tendency toclog or to bridge. Such tendency arises only when there is a downwardconstriction in the chamber from which the sawdust drops.

The central chamber will continue to empty until it is largely emptied.Some sawdust will fall in from the outside chambers, especially at theopen corners, but these outside chambers will not empty to a largedegree. Finally the pressure from one of the wedge-shaped outerchambers, inwardly upon its partition strip, will overcome theresistance of the material within the bottom of the emptying centralchamber, and this particular partition strip will swing inwardly. Indoing so, it vigorously breaks up clogging in the vicinity of thethroat. It may swing all the way across the central chamber to contact,for instance, the strip 6 with the strip 4, in the initial position ofthe latter, as shown at A. On the other hand, both the strip 4 and thestrip 5 may each swing inwardly, and may meet in an intermediateposition, as shown at B.

In either case the chamber defined between the partition. strip 6 andits adjacent hopper wall is materially increased in volume, and itsbottom is increased in cross-sectional extent until it is larger thanits top. Its bottom extent is not materially greater than the extent ofthe margin of the throat 2, for the length of the partition strips is sochosen that they cannot swing far past the opposite side of the throat.Accordingly there is now provided a further chamber at the right, whichprogressively decreases in cross sectional extent upwardly, and which isnot materially larger at the bottom than the extent of the throat. Thischamber will empty freely as originally did the central chamber, and intime this chamber will be deformed again by pressure against some otherpartition strip, the sawdust above the throat will be stirred, and eachnew chamber will be suddenly enlarged in volume, and will have itsbottom increased in plan extent, so that it will discharge freelythrough the throat.

It is conceivable that all four of the partition strips 4, 5, 6, and Imay be simultaneously swung inwardly, as shown in the dot-dash lines C.There would still be the effect of a sudden increase in the volume ofeach of the outer chambers, a stirring of sawdust at the throat, and anincrease in the extent of the bottom opening of each such outer chamber.These increases, it

- has been found, are sufiicient to permitdischarge from these outerchambers without clogging, and at some point in the operation one suchchamber will discharge more than the others, and will then beconstricted with corresponding enlargement of another chamber, which inturn will permit freer discharge from this other chamber.

It has been found that this arrangement will operate continuously andwith entire satisfaction. It is extremely simple and inexpensive, andthere is nothing to get out of order. If it is desired to gain access tothe interior of the hopper the entire assembly may quickly be liftedfrom the open top of the hopper, even if the hopper is filled, leavingthe hopper interior free and clear.

It is in the provision of a central chamber, shaped and positioned forfree and non-clogging discharge, and substantially complete discharge,directly through the throat, in advance of any substantial dischargefrom other chambers, and in the arrangement of the partition strips insuch manner that with the collapse of the central chamber one of theouter chambers is immediately enlarged at its bottom and in its volume,for similar free discharge, that this invention is to be distinguishedfrom other hopper-partitioning arrangements.

What I claim 'as my invention is:

1. In combination with the upwardly flared walls of a sawdust hopper orthe like, having an open top and a smaller open throat, a plurality ofpartition strips freely pivotally hung in the upper part of the hopperin a pattern similar to and located directly above the outline of thethroat, said partition strips being weighted to diverge slightlydownwardly, to define between them a central chamber having its largestcrosssection at its bottom not materially extending outside the outlineof the throat, and progressively diminishing in cross-section upwardlyand to define surrounding wedge-shaped chambers between each partitionstrip and the adjoining hopper wall.

2. In combination with the upwardly flared walls of a sawdust hopper orthe like, having an open top and a smaller open throat, a plurality ofpartition strips freely pivotally hung in the upper part of the hopperin a pattern similar to and located directly above the outline of thethroat, said partition strips being weighted to diverge slightlydownwardly, and of a length to contact the hopper wall, when outwardlyswun adjacent the throat, said partition strips cooperating with eachother, when hanging freely, and with the adjacent hopper walls, todefine between them a central chamber having no crosssection whichmaterially extends outside the out line of the throat, and whichincreases in crosssection from its top downwardly, and to definesurrounding wedge-shaped chambers between 7 each partition strip andeach adjacent upwardly flared hopper wall.

3. In combination with the upwardly flared walls of a sawdust hopper orthe like, having an open top and a smaller open throat, a plurality ofpartition strips freely pivotally hung in the upper part of the hopperin a closed pattern, and located directly above the throat, saidpartition strips being weighted to diverge slightly downwardly, and of alength to contact the hopper wall, when outwardly swung, adjacent thethroat, and of a width at their bottoms materially less than thecorresponding distance across the throat, said partition stripscooperating with each other, when hanging freely, to define between thema central chamber having no crosssection at its bottom which materiallyextends outside the outline of the throat, and having all cross-sectionsabove its largest cross-section of progressively decreasing extent, andsaid partition strips each further cooperating, when hanging freely,with the adjacent flared hopper wall to define an outer wedge-shapedchamber which has its smaller end downward.

4. In combination with the upwardly flared walls of a sawdust hopper orthe like, having an open top and a smaller open throat, a plurality ofpartition strips freely pivotally hun in the upper part of the hopper ina closed pattern, and located directly above the throat, said partitionstrips being weighted to diverge slightly downwardly, and of a length tocontact the hopper wall, when outwardly swung, adjacent the throat, andof a width at their bottoms materially less than the correspondingdistance across the throat, said partition strips cooperating with eachother, when hanging freely, to define between them a central chamberhaving no cross-section at its bottom which materially extends outsidethe outline of the throat, and having all cross-sections above itslargest crosssection of progressively decreasing extent, and saidpartition strips each further cooperating, when hanging freely, with theadjacent flared hopper wall to define an outer wedge-shaped chamberwhich has its smaller end downward, each partition strip being furtherso located their pivoted upper ends. with relation to the adjacenthopper wall, that when its lower end swings inwardly, upon substantialemptying of the central chamber, into contact with a partition stripopposite, the corresponding outer chamher will have a width at itsbottom not materially less than the spacing of the strips pivoted upperend from the adjacent hopper wall.

5. A clog-preventing assembly for disposition within a flared-wallhopper, comprising a plurality of pendant strips disposed in a closedpattern, and means supporting the strips from their upper ends for freeswinging movement, each independently of the others.

6. A clog-preventing assembly for disposition within a flared-wallhopper, comprising a plurality of pendant strips disposed in a closedpattern, and means supporting the strips from their upper ends for freeswinging movement, each independently of the others, said trips beingweighted to hang with their free lower ends more greatly spaced thantheir pivoted upper ends.

7. A clog-preventing assembly for disposition within a flared-wallhopper, comprising a plurality of pendant strips disposed in a closedpattern, and means supporting the strips from their upper ends for freeswinging movement, each independently of the others, said strips beingweighted to hang with their free lower ends more greatly spaced thantheir pivoted upper ends, said strips being of a length, relative to thehopper with which they are used, to extend from a suitable support inthe upper part of the hopper downwardly to a point adjacent therestricted bottom throat of the hopper.

8. A clog-preventing assembly for disposition within a flared-wallhopper, comprising a plurality of pendant strips disposed in a closedpattern, and means supporting the strips from their upper ends for freeswinging movement, each independently of the others, said strips beingnarrower at their lower ends than the width of the pattern in which theyare arranged.

9. A clog-preventing assembly for disposition within a flared-wallhopper, comprising a rectangular horizontal frame, a pendant strip ofsheet metal or the like freely pivotally mounted upon each side of saidframe, and weighted to swing outwardly at its lower end, each stripbeing narrower at its lower end than the length of its side of theframe.

10. In combination with the upwardly flared walls of a sawdust hopper orthe like, having an open top and a smaller open throat, a plurality ofpartition strips freely pivotally hung in the upper part of the hopperin a pattern similar to and located directly above the outline of thethroat, said partition strips defining between them a central chamberhaving no cross-section which materially extends outside the outline ofthe throat, and said partition strips also cooperating with the adjacenthopper walls to define wedge-shaped chambers surrounding th centralchamber, and each capable of merging thereinto at the bottom by inwardswinging of the corresponding partition strip, after substantialemptying of the central chamber, under pressure of the material retainedin such wedge-shaped chamber.

EMIL ZIMMERMAN.

